The present invention is directed generally to data terminals, and more particularly to a teleprinter incorporating an improved print head carriage and removable ink ribbon cartridge.
In recent years the increased use of data-based communication systems has led to the need for economical high speed data terminals whereby information conveyed by electrical signals is converted to printed copy on paper or other suitable print-retaining surface. Typically, such teleprinters incorporate an impact-type print head, which impacts the paper against a platen as the print head moves across the paper, causing impressions to be made on the paper by an inked ribbon or by chemical transformation of the paper. One particularly successful form of impact-type print head is the dot matrix-type print head, wherein selected ones of a plurality of elongated rod-shaped print wires arranged in a predetermined array are forced against the paper to form the desired characters as the print head is stepped across the page. A preferred colinear construction for such a print head is shown in the copending application of Robert C. Hoffman, Richard H. Kruse, and Donald P. Martin, Ser. No. 038,923, filed concurrently herewith and assigned to the present assignee.
In order for a teleprinter to be suitable for use in a large number of applications, it is desirable that the teleprinter be economical, compact and reliable in construction. To this end, it is desirable that the carriage mechanism provided in the teleprinter for positioning the print head be constructed with as few components as possible, and that the components utilized be arranged in a compact manner to allow the smallest possible housing. Furthermore, for sharp consistent print images it is necessary that the print head be accurately and reliably positioned by the carriage, not only during the printing of each line, but also during carriage return and line feed operations. Heretofore, print head carriage arrangements for positioning the print head with the necessary precision have been unnecessarily complex, and have therefore unnecessarily added to the cost of teleprinters. Representative prior art print head carriage arrangements are described in U.S. Pat. Nos. 3,960,256, 3,949,857 and 3,670,861.
With impact printers it is conventional practice to place an inked ribbon between the print elements of the print head and the paper to form a visible impression on the paper at each impact location. Typically, this inked ribbon is contained on two spools, at least one of which is periodically driven with movement of the print head to cause the ribbon to be advanced from one spool to the other, thereby exposing the paper to a continuously changing unused portion of the ribbon to provide a consistently legible print image. Heretofore the mechanisms for advancing teleprinter print head ribbons have been relatively complex, and have unnecessarily added to the cost of the teleprinter and to the time and expense of periodic maintenance. Furthermore, the complexity of the prior-art ribbon drive arrangements has heretofore precluded the use in teleprinters of pre-loaded ribbon cartridges, wherein the inked ribbon can be conveniently changed by merely substituting one cartridge for another, without the necessity of threading the ribbon between spools or ribbon guards, or physically handling the ribbon.
The present invention is directed to a new and improved print head carriage, and to a new and improved removable inked ribbon cartridge for the carriage, which provide improved economy, reliability and convenience of operation in an impact-type teleprinter.
Accordingly, it is a general object of the present invention to provide a new and improved teleprinter which is economical, reliable and compact in construction.
It is a more specific object of the present invention to provide a new and improved print head carriage assembly for a teleprinter which is compact, reliable and economical in construction.
It is another specific object of the present invention to provide a new and improved print head carriage assembly for a teleprinter wherein the inked ribbon associated with the carriage is contained in a readily removable cartridge.
It is another specific object of the present invention to provide a new and improved print head carriage assembly wherein the inked ribbon carried thereon is automatically advanced with movement of the carriage.
It is another general object of the present invention to provide a new and improved removable inked ribbon cartridge for a teleprinter.